A major defense contractor has come to the aid of a stalled federal probe of the collapse of World Trade Center building 7, which housed Defense Department and CIA offices, after a previous WTC 7 study was quietly killed by the government.

The contract to Applied Research Associates Inc., of Albuquerque, N.M., supersedes a contract to the New York engineering firm of Gilsanz Murray Steficek,
whose study of the WTC7 collapse never reached the public. Ramon Gilsanz had co-authored a 2002 federal report that expressed strong doubts about WTC7's collapse.

ARA was awarded a contract by the National Institutes of Technology and Standards, or NIST, to detect the initial cause of collapse and to come up with a computer simulation of the crash.

The NIST specified that the contractor must use data provided by the federal agency for its computer simulations.

The NIST has employed the firm, based in Albuquerque, N.M., in previous WTC collapse technical work. The monetary value of the contract was not published on the NIST web site.

ARA, which has expertise in computer simulations of the destructive effects of explosive weapons, received $318 million in defense contracts between 1998 and 2003, according to the Center for Public Integrity advocacy group.

The NIST issued its final reports on the collapses of WTC 1 and 2 in September 2005 after quietly "decoupling" the WTC7 probe from its investigation, citing staffing difficulties. The NIST said its WTC7 draft report was scheduled for release in October 2005, with a final report ready in December 2005.

However, that deadline was not met and in January 2006 the NIST sought bids for research into the WTC7 collapse, with ARA awarded a contract on March 31, 2006.

Previously, the NIST awarded a contract to Ramon Gilsanz and his New York engineering firm to do computer simulations of the WTC7 collapse. Dropped from the NIST website was the report titled "Structural Analysis of the response of World Trade Center 7 to debris damage and fire" (denoted NCSTAR 1-6F) by Gilsanz and nine others. No explanation was given, though presumably this report was to have been used as evidence supporting the NIST theory.

A 2002 Federal Emergency Management Agency, or FEMA, report on WTC7 co-authored by Gilsanz said the idea that fire triggered WTC7's collapse had "low probability."

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The government's stance on the collapse of the 47-floor WTC7 has raised eyebrows of experts, including researchers working with Gilsanz on a FEMA report, and, more recently, a Brigham Young University physics professor.

Jones and his students clocked a downward sequence of blasts of smoke ejected from WTC7 windows at two-tenths of a second apart.

Some have attributed World Trade Center belches of smoke to dust expelled as floors crashed downward onto other floors. However, the basic gravity equation (y = 1/2gt2) proves that in two-tenths of a second a floor could have dropped no more than eight inches. A six-foot fall takes at least six-tenths of a second.

Also, Jones observed a sequence of upwardly climbing blasts from WTC7, which he says are consistent with what is commonly known about controlled demolitions.

The NIST has reported that no steel debris was recovered from WTC7 and so no forensic analysis of the steel was possible.

In response to Jones and others, the NIST has inserted a note in its reports saying it had found no evidence of building destruction by missiles, bombs or controlled demolition. However, the agency cites no supporting data to show what work was done to preclude these possibilities.

Such a note is found in a report titled "Part IIC -- WTC 7 collapse," which contains a working hypothesis of fire-induced collapse, a series of graphics and photos and sketchy ideas about what might have happened. It contains no data on the sequential puffs of smoke seen by Jones.

Though dated April 2005, the report was not available during last year's public comment period for the twin towers report.

At 5:20 p.m., some seven hours after WTC1 fell, WTC7 collapsed almost straight down, indicating collapse must have begun on a lower floor, federal probers have said.

In a March 2005 Popular Mechanics article, "9/11: debunking the myths," lead NIST investigator Shyam Sunder is quoted as saying that new evidence indicated that WTC7 showed severe structural damage following the tower collapses and that this weakening, abetted by a longterm fire, was the agency's working hypothesis.

Some 10 lower stories, or about 25 percent of the building vertically, was "scooped out," he is reported to have said. (The previous FEMA report also cited such damage, but did not regard it as compelling.)

Yet an NIST report (NCSTAR 1-3), says the NIST made no effort to check high-strain or impact properties of the type of steel used in WTC7 because "WTC7 did not suffer any high strain rate events."

In the magazine, Sunder said that an oddball design implied that failure of even one column on a lower floor might trigger collapse and suggested that a fuel-oil-fed fire contributed critical weakening.

However, an NIST report (NCSTAR 1-1J), found that the standard safeguards for the building's several fuel-oil systems would likely have blocked a longterm fuel-oil-fed fire, an idea first mentioned by FEMA probers.

The most likely source of leaking fuel would have been the Salomon Brothers system, NCSTAR 1-1J says, with probers citing two possibilities: a fuel spill from the 250-gallon "day tank" on the fifth floor or fuel continually pumped up from an underground tank, but they suggest that failsafes should have worked.

NIST-contracted probers Raymond A. Grill and Duane A. Johnson say it is barely conceivable that an electrical malfunction caused pumps to keep bringing up fuel from a 6,000-gallon tank buried underground. But they are puzzled as to the source of the electricity. Power to the building would have been shut off the morning of Sept. 11, though the building's emergency generators are powered by fuel oil.

The electrical schematics for the fuel system are missing, along with building maintenance records that might have yielded clues to the electrical system.

In FEMA's May 2002 report on the World Trade Center collapses, investigators wrote: "Although the total diesel fuel on the premises contained massive potential energy, the best hypothesis" for a fire-fed building collapse "has only a low probability of occurrence." They demanded further inquiry into how key supports could have given way.

In November 2001, New York Times reporter James Risen disclosed that WTC7 had housed the CIA's New York station and that on Sept. 11 a CIA team had scoured the trade center site seeking secret documents and other classified material. Risen's report did not say whether the CIA had searched the site prior to WTC7's collapse, though that scenario seems highly likely.

The FEMA report confirmed the CIA presence and also said the Defense Department had offices in the building.

It has been reported that Larry A. Silverstein, the real estate man who ran the trade center, told a PBS reporter that he gave the go-ahead to the "er, Fire Department" to "pull" the building. A search of the PBS site for the interview proved fruitless, but Silverstein has put out a statement saying the FEMA report has determined that fire was responsible for WTC7's collapse.

The 9/11 commission, which concluded that 9/11 was a consequence of bureaucratic bungling, issued its report in June 2004, more than a year before the NIST's final report on the twin towers collapse.
The NIST, in its inquiry into the collapse of the twin towers, makes no point of having consulted experts on the controlled demolition of buildings.